This sections provides background information related to the present disclosure which is not necessarily prior art.
Such coupling assemblies are known in various embodiments in vehicle technology and usually serve for decoupling and/or coupling sections of the powertrain of a motor vehicle.
In particular, coupling assemblies of the generic type are used in all-wheel drive motor vehicles and in motor vehicles with hybrid drive. They serve in particular for deactivating sections of the powertrain, in order to prevent unnecessary corotation and thus unnecessary energy consumption of the sections of the powertrain being deactivated.
PCT Patent Application No. WO 2011/098595 A1 thus describes a coupling assembly of the generic type. In this system an actuating mechanism is formed for actuating a clutch, the actuating mechanism selectively bringing an engaging portion into engagement with a threaded portion that co-rotates with a shaft. In this way, a relative movement is effected of the engaging portion and the threaded portion along an axis of the rotating shaft, thus resulting in the clutch being displaced (decoupled) in the axial direction.
Similarly, PCT Patent Application No. WO 2013/186076 A1 describes a power transmission unit having an integrated disconnect mechanism. The disconnect mechanism comprises a positive-locking clutch, in which a sliding sleeve interacts in a positive-locking manner with another shaft component. The actuating mechanism for actuating the clutch is a sector nut. The sector nut is brought into engagement, by way of an actuator, with a thread in the input shaft. The thread runs in such a way that the sector nut engaged by the actuator displaces the sliding sleeve in the decoupling direction.
German Patent Application No. DE 10 2009 005 358 A1, for example, describes a powertrain for a motor vehicle having a full-time driven primary axle that includes a drive unit for generating a drive torque, and a first clutch for transferring a variable portion of the drive torque to a secondary axle of the motor vehicle. In addition, the powertrain has a second clutch for deactivating a torque-transmitting portion of the powertrain arranged between the first clutch and the second clutch, when the first clutch is open.
The aforementioned coupling assemblies serve for reversibly deactivating sections of the powertrain of a motor vehicle, in particular a secondary section of a powertrain. In order to ensure a positive decoupling of the clutch and thus positive deactivation of a section of the powertrain, the threaded portion of the actuation device is always connected in a rotationally fixed manner to a shaft that always rotates when the vehicle is in motion. In other words, the threaded portion of the actuation device of the coupling assembly is always arranged on a section not adapted to be deactivated of the powertrain of the motor vehicle. This solution often requires a relatively large installation space and complex integration into the powertrain.
If, in the embodiments described in the prior art, the threaded portion were to be arranged on a shaft or construction element and/or sub-assembly of the powertrain that comes to a standstill while vehicle is in motion, or in a powertrain section to be deactivated, the following effect could occur: the decoupling process of the clutch is started and the clutch will be opened until it becomes disengaged—the section to be deactivated of the powertrain comes to a standstill, but the decoupling process is not fully completed, as a result of which, for example, a rasping noise on the clutch may occur.
Furthermore, all of the above coupling assemblies of the prior art are sensitive to excessive torque introduced by way of the threaded portion. For example, it has not been possible so far to integrate the threaded portion on a differential case, because the torque required for the clutch to be opened for positive rotation of the differential case, if it were too high, is acoustically perceptible during decoupling of the clutch as a powertrain decompression shock.